AQP4 is expressed in human and mouse placenta. AQP4 immunoreactivity in (A) human ovary (H-OVARY), (B) human uterus (H-UTERUS), and (C) human placenta (top; H-PLACENTA; 20 and 40 wk gestation), AQP4 immunofluorescence in 20 wk human placenta (bottom left), and human placental AQP4 versus gestational age (bottom right). AQP4 immunoreactivity in (D) mouse ovary (M-OVARY), (E) mouse uterus (M-UTERUS), (F) mouse placenta (left; M-PLACENTA; E10, E13, E17, and E18). KO is AQP4 null mouse. Red arrowheads show AQP4. Mouse placental AQP4 versus gestational age is shown (right). (G) Binding of i.p. injected NMO-IgG58[Cy3] or CON-IgG2B4[Cy3] to placenta (WT or KO mouse). Tissue was double-stained (FITC) with commercial anti-AQP4: blue (DAPI), green (FITC), red (Cy3), and yellow (Merge). Scale bars, 20 μm (C, F), 50 μm (A, D, E, G), and 100 μm (B). Ce, Cervix; Cx, cortex; En, endometrium; Fo, follicle; My, myometrium; Pe, perimetrium.